| Apparatus, system, and method for amplitude-phase synchronization in polar transmitter -> Monitor Keywords |
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  Apparatus, system, and method for amplitude-phase synchronization in polar transmitterRelated Patent Categories: Pulse Or Digital Communications, TransmittersThe Patent Description & Claims data below is from USPTO Patent Application 20070230612. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND [0001] Polar modulation is a technique whereby a signal, or carrier, having constant radian frequency .omega., is time-varied in both magnitude and phase. Polar modulation transmitters transmit information that both the magnitude (R) and the phase (.theta.) of a signal simultaneously carry. There are many benefits to using polar modulation to transmit information. Polar transmitters receive baseband signals represented in Cartesian form as an in-phase (I) component and a quadrature (Q) component. The I/Q baseband signals are naturally symmetric at the source. The I/Q baseband signals are converted to polar form in terms of its magnitude R and phase .theta. signals. The magnitude R is referred to as the amplitude signal and the phase .theta. is referred to as the phase signal. A coordinate rotation digital computer (CORDIC) algorithm may be employed to convert the I/Q baseband signals to polar form amplitude R and phase .theta. signals. The amplitude R and phase .theta. signals are processed in separate amplitude and phase paths and may be recombined at the output of the power amplifier. The I/Q components may be reconstructed by additional processing downstream of the power amplifier output. [0002] Circuits for processing the amplitude R and phase .theta. signals in the respective separate amplitude and phase paths are substantially different and may lead to timing misalignments between the amplitude and phase signals. Unlike the natural symmetry of the I/Q baseband signals at the source, the amplitude R and phase .theta. signals are asymmetric, and thus, there are timing misalignments between them. The timing misalignment between these signals is detrimental to the reconstructed I/Q component. Accordingly, in polar transmitters, there is a need to synchronize the amplitude R and phase .theta. signals to correct for the timing misalignments due to different delays encountered by these signals in the separate amplitude R and phase .theta. processing paths. Therefore, there is a need for techniques to determine and correct for delays in the amplitude R and phase .theta. processing paths. There is a need to estimate and correct for these timing misalignments in an accurate manner. SUMMARY [0003] In one embodiment, a modulation path synchronization apparatus in a polar transmitter includes a modulation path to receive a training waveform, a detector coupled to the modulation path, the detector to detect a modulated training waveform, and a processor coupled to the detector, the processor to determine a delay between the training waveform and the modulated training waveform. [0004] In one embodiment, a method to synchronize modulation paths in a polar transmitter includes passing a baseband amplitude training waveform in an amplitude modulation path; detecting a carrier envelope of a first amplitude modulated training waveform associated with the amplitude training waveform; and determining an amplitude modulation path delay. [0005] In one embodiment, a system to synchronize modulation paths in a polar transmitter includes an amplifier and a modulation path coupled to the amplifier to receive a training waveform, a detector coupled to the modulation path, the detector to detect a modulated training waveform, and a processor coupled to the detector, the processor to determine a delay between the training waveform and the modulated training waveform. BRIEF DESCRIPTION OF THE DRAWINGS [0006] FIG. 1 illustrates one embodiment of an amplitude modulation path synchronization system. [0007] FIG. 2 illustrates one embodiment of a phase modulation path delay synchronization system. [0008] FIGS. 3A, B, C, D graphically illustrates various embodiments of waveforms in a phase modulation path synchronization system. [0009] FIG. 4 illustrates one embodiment of a combined amplitude and phase modulation path synchronization system. [0010] FIG. 5 illustrates one embodiment of a detector adapted for an amplitude and phase modulation path synchronization system. [0011] FIG. 6 graphically illustrates one embodiment of an AM waveform. [0012] FIG. 7 illustrates one embodiment of a combination amplitude and phase modulation path synchronization system. [0013] FIG. 8 illustrates one embodiment of a combination amplitude and phase modulation path synchronization system. [0014] FIG. 9 illustrates one embodiment of an amplitude and phase modulation path synchronization system. [0015] FIG. 10 is a flow diagram of one embodiment of a synchronization process to determine a delay in an amplitude modulation path of an RF transmitter in a polar modulation topology. [0016] FIG. 11 is a flow diagram of one embodiment of a synchronization process to determine a delay in a phase modulation path of an RF transmitter in a polar modulation topology. [0017] FIG. 12 is a flow diagram of one embodiment of a process to estimate delay in an amplitude path and a phase path simultaneously. [0018] FIG. 13 is a flow diagram of one embodiment of a process to estimate delay in an amplitude path and a phase path simultaneously. DETAILED DESCRIPTION [0019] Embodiments of various implementations of a path delay estimation techniques to estimate and correct timing misalignments between amplitude and phase processing paths in a polar modulation topology transmitter are disclosed and claimed. Polar domain amplitude R and phase .theta. signal representations of I/Q baseband signals are employed to accurately estimate and correct amplitude and phase path timing misalignments (delay mismatches). These techniques may be integrated with circuits and modules in polar transmitter integrated circuit (IC) devices. [0020] In one embodiment, a path delay estimation system calculates estimated amplitude modulation path delay and phase modulation path delay in separate steps (two-step method). In a first step, the system may estimate amplitude modulation path training mode and, in a second step, the system may estimate the phase modulation path delay. It will be appreciated that the order of the first and second steps may be reversed without limitation. In one embodiment, a path delay estimation system calculates estimated amplitude and phase modulation path delays in single-step or two-step method. In one embodiment, a path delay estimation system calculates estimated amplitude and phase modulation path delays simultaneously. In various embodiments, training waveforms may be passed through each amplitude and phase modulation paths simultaneously during the synchronization training period. Accordingly, amplitude and phase training waveforms are passed through respective amplitude and phase paths simultaneously. In the two-step method, input training waveforms are passed through the amplitude and phase paths of the polar transmitter separately. The estimated delay in each path is also obtained separately. The input training waveforms comprise a periodic waveform at a predetermined frequency, amplitude, and shape or form. The input training waveforms are amplitude-modulated (AM) or frequency-modulated (FM) at the power amplifier (PA) with a carrier waveform based on whether the path delay estimation system is operating in amplitude training mode or phase training mode, respectively. The carrier waveform comprises a periodic waveform at a much higher frequency than the input training waveform. At the output of the PA, the AM or FM training waveforms are detected and correlated with the respective input training waveform to estimate a delay for the respective amplitude or phase path. Detection and correlation techniques may differ based on whether the path delay estimation system is in amplitude path training mode or phase modulation path training mode. In one embodiment, the training waveform may be a sine wave at a frequency referred to as a tone. Although a "sine wave tone" may be referred to herein, it is to be understood that a sine wave tone is used merely to simplify the description. The embodiments are in no way intended to be limited to any particular waveform shape, magnitude, or frequency. Any waveform and/or frequency may be used to generate the training waveforms, carrier waveforms, modulation waveforms, and the like. Continue reading... Full patent description for Apparatus, system, and method for amplitude-phase synchronization in polar transmitter Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Apparatus, system, and method for amplitude-phase synchronization in polar transmitter patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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